Short interval timer



Aug. 5," 1969 s. R. FROST SHORT INTERVAL TIMER Filed March 15. 1967 United States Patent 3,458,990 SHORT INTERVAL TIMER George Russey Frost, Champaign, I1l., asslguor to University of Illinois Foundation, Urbana, Ill., a corporation of Illinois Filed Mar. 15, 1967, Ser. No. 623,351

Int. Cl. G04f 1/06' US. Cl. 58144 7 Claims ABSTRACT OF THE DISCLOSURE Disclosed is a simple short interval timer based on displacement of a gas bubble in a liquid filled tube. The timer includes means to instantly stop movement of the bubble when the time interval ends, regardless of the length of the interval within the limits of the timer.

This invention relates to timing devices. More particularly, this invention is concerned with a timing device operated by gravity for measuring short intervals.

The measurement of time intervals is fundamental to many experiments in the physical and biological sciences. Stop watches or electronic timers can be used for shorttirne interval measurements but these devices are costly. Cost and fragileness preclude their use by pupils in grammar school and even in many high schools. As a result, the pupils are denied the opportunity to use instruments for short-time interval measurements and thus prevented from experiencing the relationship between these intervals and natural phenomena. There is accordingly an existing need for an inexpensive simple short-time interval measuring device which can be readily used by school upils.

P There is accordingly provided by this invention a short interval timer comprising: an elongated tubular element, said tubular element being of clear, light-permeable material; a liquid, together with a small gas bubble, in the tubular element; each end of the tubular element being closed air and liquid tight; means for movably supporting the tubular element horizontal thus maintaining the bubble static; guide means for temporarily positioning the tubular element at a predetermined angle to the horizontal upon the application of a force thereto thus effecting upward movement of the bubble in the tubular element; rotation means for returning the tubular element to the horizontal position upon release of said force thus terminating movement of the bubble; and a scale associated with the tubular element which translates distance traveled by the bubble into time units.

The invention will be described further in conjunction with the attached drawings in which:

FIGURE 1 is a perspective view of one specific embodiment of the short interval timer of this invention;

FIGURE 2 is a plan view of the timer of FIGURE 1;

FIGURE 3 is a side elevational view of the timer of FIGURES 1 and 2;

FIGURE 4 is similar to FIGURE 3 but shows the timer in operation;

FIGURE 5 is a sectional view taken on the line 55 of FIGURE 3;

FIGURE 6 is a sectional view of FIGURE 2 along the line 6-6.

For convenience and clarity, the same elements or parts in the various views of the drawings will be identified by the same numbers.

As shown in the drawings, the short interval timer has an elongated tubular element 10 which can be of any suitable material although clear glass or plastic which is light-permeable is advisably used. The tube 10 contains a liquid 11, usually water, and a small gas bubble 12, usu- 3,458,990 Patented Aug. 5, 1969 ice tube bubble 12 is static. Projecting outwardly and upw wardly from central portion A on the bottom of rocker body 15 are inclined surfaces 16 and 17. The angles of inclination of surfaces 16 and 17 are different, with surface 17 being inclined about four to five times more than surface 16. A longitudinal groove 19 in rocker body 15 helps to maintain tube 10 secure against unwanted movement. Linear scales 20 and 21, in units of time, are axially placed on each side of tube 10, advisably on the top surface of rocker body 15. Each scale is different and calibrated to convert movement of bubble 12 into units of time.

Rocker body 15 rests on base 18, which is essentially a rectangular block of wood or other suitable material. Rubber bands 22 and 23 serve as springs or rotation means to return the rocker body 15 to the horizontal position after being displaced angular thereto. Grooves 24 are provided in base 18 to receive the rubber bands in recessed position so that the base can rest firmly on a surface such as a table or work bench.

In a specific embodiment of the timer, a glass tube can be used 6 inches long by 10 mm. outside diameter, and a rocker body and a base 7 inches long and inch wide. The rocker body can be inch high and have a flat central portion 1% inches long. Inclined portions 16 and 17 can each be 2% inches long with portion 16 inclining inch, and portion 17 inclining inch, for such distances. With these dimensions, one scale can measure time intervals up to a maximum of two seconds while the other scale measures time intervals up to a maximum of 15 seconds. Of course, by increasing the length of the tube and/or varying the displacement angle for the tube 10, different time intervals can be measured.

The short interval timer operates by gravity. When the tube 10 is horizontal, the bubble remains static or motionless in the tube regardless of its specific position any- Where along the top inside of the tube. When the tube is tilted, the bubble moves to the high end of the tube. By maintaining a constant angle of tilt from the horizontal, the bubble moves along the inside of the tube at a constant velocity. By calibrating displacement of the bubble with a standard time source, scale markings can be applied alongside tu'be 10 to obtain appropriate time interval readings.

The inclined surfaces 16 and 17 on the bottom of rocker 15 provide guide means for temporarily positioning tube 10 at a predetermined angle to the horizontal upon the application of force. As shown in FIGURE 4, hand 25 has applied force on one end of the rocker 15 to rotate it and place surface 17 in contact with base 18, carefully positioned horizontal. As a result, bubble 12 moves from its position as shown in FIGURE 3 to the position shown in FIGURE 4. Movement of bubble 12 is instantly stopped by quickly rotating tube 12 to the horizontal position. This is readily done 'by removing the force applied by hand 25, thus permitting rubber band 22 to immediately pull the rocker body 15 back into horizontal position with central portion A flat against the base 18. Pushing down the other end of the timer and then releasing it also gives a time interval measurement. However, since the angle of displacement would be less, longer time intervals can be measured because movement of the bubble would be slower than when the other end of the timer is pressed down.

Although the drawing shows a timer having two inclined surfaces 16 and 17, only one need be provided. Furthermore, any other structure which permits rotation of rocker body 15 to a predetermined angle to the horizontal can be used as a guide means in place of one or both of the inclined surfaces 16 and 17.

While rubber bands provide suitable spring means for quickly returning tube to the horizontal, spring means of metal such as coil springs or strip springs can be used in place of rubber bands.

Various changes and modifications of the invention can be made to the extent that such variations incorporate the spirit of this invention.

What is claimed is:

1. A short interval timer comprising:

.an elongated internally-unobstructed tubular element of clear, light-permeable material,

a liquid, together with a small gas bubble, in the tubular element,

each end of the tubular element being closed air and liquid tight,

means for movably supporting the tubular element horizontal thus maintaining the bubble static .at any position in the tubular element,

guide means for temporarily positioning the tubular element at a predetermined angle to the horizontal upon the application of a force thereto thus effecting upward movement of the bubble in the tubular element,

rotation means for quickly returning the tubular element to the horizontal position upon release of said force thus terminating movement of the bubble and rendering it static at the place it is in the tubular element when the force is released, and

a linear scale positioned axially to the tubular element which translates distance traveled by the bubble into time units.

2. A timer according to claim 1 in which the tubular element is colorless glass or a clear plastic material.

-3. A timer according to claim 1 in which the rotation means is a spring of metal or elastic material.

4. A short interval timer comprising:

.an elongated internally-unobstructed tubular element, said tubular element being of clear, light-permeable material,

a liquid, together with a small gas bubble, in the tubular element,

each end of the tubular element being closed air and liquid tight,

means for movably supporting the tubular element horizontal thus maintaining the bubble static at any position in the tubular element, said means comprising a rocker body having a flat horizontal bottom portion,

guide means for temporarily positioning the tubular element at a predetermined angle to the horizontal upon the application of a force thereto thus effecting upward movement of the bubble in the tubular element,

rotation means for quickly returning the tubular element to the horizontal position upon release of said force thus terminating movement of the bubble and rendering it static at the place it is in the tubular element when the force is released, and

a scale associated with the tubular element which translates distance traveled by the bubble into time units.

5. A timer according to claim 4 in which the guide means for temporarily positioning the tubular element at a predetermined angle to the horizontal is an inclined surface on the underside of the rocker body.

6. A timer according to claim 5 in which the underside of the rocker body has two inclined surfaces projecting upwardly and outwardly from the flat horizontal bottom portion.

7. A timer according to claim 5 in which the rocker body is supported by a fiat topped base secured thereto and the rotation means is a spring of metal or elastic material balanced to maintain the flat portion of the rocker body in horizontal position on the base top and to return it to such position upon release of force which angles the tubular element to the horizontal.

References Cited UNITED STATES PATENTS 2,234,437 3/1941 Kistler 58-444 FOREIGN PATENTS 589,384 2/1924 France.

EDITH C. SIMMONS, Assistant Examiner RICHARD B. WILKINSON, Primary Examiner 

